Hi Loose54,
I've heard it said that one picture is worth a thousand words, and when it comes to coin die varieties, no truer words have ever been spoken. To see the subtle differences between Freeman obverses 15, 16 , and 19, have a look at the photos of the Nicholson collection on the Colin Cooke website:
Go to: colincooke.com
Select: "Other", "Collections", "Dr. Basil Nicholson Collection of Halfpennies", "Part 5"
Then:
Items 455 & 457 = Freeman 340 & 342 = Obverse 15
Item 459 = Freeman 344 = Obverse 16
Items 460, 461, & 462 = Freeman 347 & 351 = Obverse 19
Let me know how this solution works for you. I can provide high resolution photos of those Obverse dies, if necessary.